sequenceDiagram
    participant App as 用户服务
    participant Pool as MySQLPool
    participant Queue as 连接池队列
    participant DB as MySQL服务器
    
    App->>Pool: GetConnection()
    activate Pool
    Pool->>Queue: 尝试获取连接
    activate Queue
    Queue-->>Pool: 返回连接 conn
    deactivate Queue
    Pool-->>App: 返回连接
    deactivate Pool
    
    App->>DB: 执行SQL查询
    activate DB
    DB-->>App: 返回结果
    deactivate DB
    
    App->>Pool: ReturnConnection(conn)
    activate Pool
    Pool->>Queue: 归还连接
    activate Queue
    Queue-->>Pool: 完成
    deactivate Queue
    Pool-->>App: 完成
    deactivate Pool
    
    Note over App,DB: T0: 请求连接 (0ms)
    Note over App,DB: T1: 获取连接 (1-5ms)
    Note over App,DB: T2: 执行查询 (5-50ms)
    Note over App,DB: T3: 归还连接 (0ms)
    Note over App,DB: 总耗时: ~6-55ms
